Hinged vehicle chassis

ABSTRACT

A robotic vehicle chassis is provided. The robotic vehicle chassis includes a first chassis section, a second chassis section, and a hinge joint connecting the first and second chassis sections such that the first and second chassis sections are capable of rotation with respect to each other in at least a first direction. The vehicle includes a drive wheel mounted to one of the first and second chassis sections and an omni-wheel mounted to the other of the first and second chassis sections. The omni-wheel is mounted at an angle orthogonal with respect to the drive wheel. The hinge joint rotates in response to the curvature of a surface the vehicle is traversing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/137,168, filed Apr. 25, 2016, now U.S. Pat. No. 9,849,925, issuedDec. 26, 2017, which is a continuation of U.S. application Ser. No.14/553,862, filed Nov. 25, 2014, now U.S. Pat. No. 9,321,306, issuedApr. 26, 2016, which is based on and claims priority to U.S. ProvisionalPatent Application Ser. No. 61/910,323, filed on Nov. 30, 2013, each ofwhich is hereby incorporated by reference as if expressly set forth intheir respective entireties herein.

FIELD OF THE INVENTION

The present invention relates to vehicles and, in particular, roboticinspection vehicles.

BACKGROUND

In the past, there have been different inspection vehicle designs thatare used to inspect various structures, such as factory equipment,ships, underwater platforms, pipelines and storage tanks. If a suitableinspection vehicle is not available to inspect the structure, analternative is to build scaffolding that will allow people access toinspect these structures, but at great cost and danger to the physicalsafety of the inspectors. Past inspection vehicles have lacked thecontrol necessary to inspect such surfaces effectively. There aredifferent ways of controlling and providing translational forces tovehicles, however, many of these systems are designed forgravity-dependent transport, whether the goal is to overcome gravity orsimply use it.

The present invention provides a solution for providing vehicularmovement in non-gravity-dependent operations, where the impact ofgravity on vehicle movement can be minimized while still enablingversatile control. As well, the present invention is capable ofeffectively navigating a variety of curved surfaces such as pipes andvessels, as this is one possible use of the invention.

SUMMARY

According to an aspect of the present invention, a robotic vehiclechassis is provided. The vehicle chassis includes a first chassissection, a second chassis section, and a hinge joint connecting thefirst and second chassis sections such that the first and second chassissections are capable of rotation with respect to each other in at leasta first direction. The vehicle includes a drive wheel mounted to one ofthe first and second chassis sections and an omni-wheel mounted to theother of the first and second chassis sections. The omni-wheel ismounted at an angle orthogonal with respect to the drive wheel. Thevehicle includes at least a first magnet connected to at least the drivewheel or the chassis section to which the drive wheel is mounted and atleast a second magnet connected to at least the omni-wheel or thechassis section to which the omni-wheel is mounted. The at least firstand second magnets maintain and attractive force between the firstchassis section and the surface and the second chassis section and thesurface, respectively, wherein the surface is ferromagnetic. The hingejoint of the vehicle rotates in response to the curvature of a surfacethe vehicle is traversing.

According to a further aspect, the robotic vehicle chassis furthercomprises a spring element extending between the first and secondchassis section, the spring element providing a force that urges thefirst and second chassis sections into a normal position in which thereis a zero degree of rotation between the first and second chassissections.

According to a further aspect, the first and second chassis sectionsinclude separate power sources and motors for driving the drive wheeland the omni-wheel separately.

According to a further aspect, the omni-wheel includes a first andsecond set of rollers wherein the rollers maintain at least two pointsof contact with the surface.

According to a further aspect, the first and second set of rollers aresupported by a first and second hub, respectively, where the first andsecond hubs are configured to rotate freely with respect to each other.

According to a further aspect, the drive wheel includes a first andsecond drive hub, wherein the first and second drive hubs are configuredto selectively rotate freely with respect to each other.

According to a further aspect, the contact surfaces of the drive hubsare curved such that each side of the driving wheel contacts the surfaceat a single point.

According to a further aspect, the points of contact of the drive hubsare textured.

According to a further aspect, the points of contact of the drive hubsare knurled.

According to a further aspect, the points of contact of the drive hubsare coated.

According to a further aspect, the points of contact of the drive hubshave a rubber coating.

According to a further aspect, the points of contact of the drive hubshave a polyurethane coating.

According to a further aspect, a single power source provides power tothe first and second chassis sections and motors for driving the drivewheel and the omni-wheel.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates a vehicle having a hinged chassis;

FIG. 2 illustrates additional features of a vehicle;

FIG. 3 illustrates a vehicle having a hinged chassis on a curvedsurface;

FIG. 4A illustrates a schematic of a vehicle having a hinged chassis ona curved surface; and

FIG. 4B illustrates a schematic of a vehicle having a hinged chassis ona flat surface.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Referring to FIG. 1, a robotic vehicle 810 in accordance with anembodiment of the invention is shown. The robotic vehicle 810 includes afirst chassis section 812 and a second chassis section 814. A drivewheel 816 is connected to the first chassis section 812 and anomni-wheel 818 is connected to the second chassis section 814. Eachchassis section can include a control module 813, 815. Each controlmodule can include a motor, drive assembly for transferring mechanicalpower from the motor to the wheels, a power source (e.g., battery), anda controller that can control the operation of the vehicle by processingsensed data, processing stored instructions, and/or processing controlinstruction/signals received from a remote computer/operator. Thecontrol modules 813, 815 can also be connected by a flexible cable sothat power and control instructions can be shared between the twomodules.

The first and second chassis sections are connected together via aconnection that provides a degree of freedom between the two chassissections, such as a hinge 820. The hinge 820 can by of several differenttypes, including a knuckle/pin hinge or ball and detent hinge, forexample. Other types of structures can be used to provide a degree offreedom between the two chassis sections. For example, a flexiblematerial (e.g., flexible plastic) can be used to connect the two chassissections together while providing the degree of freedom between the twochassis sections. The hinge 820 provides a degree of freedom of movementbetween the first and second chassis sections. In particular, chassissections 812, 814 are rotatable through a range of degrees, with respectto each other as indicated by arrow “A” about the hinge 820. Asdiscussed in more detail below, the range of degrees of rotation betweenthe first and second chassis sections 812, 814 provides flexibility ofmovement for the vehicle 810 to traverse curved surfaces while the drivewheel 816 and omni-wheel 818 remain in contact with and normal to thecurved surface. The hinge can also have some play in the connection thatpermits a limited degree of side-to-side movement. The play can be aresult of a loose fit between the joints of the hinge or the materialused (e.g., plastic that permits some twisting). The play can permit thechassis sections to slightly move side-to-side and/or twist. This playcan improve the function of the robot as it moves along particulartrajectories that induce a twisting motion between the two chassissections, such as when the vehicle is traveling in a helical patternaround a pipe.

Referring now to FIG. 2, a simplified sketch shows the orientation ofthe drive wheel 816 and the omni-wheel 818, without illustrating thehinged chassis. In the robotic vehicle's preferred direction of travel,which is indicated by arrow “D,” the drive wheel 816 of the roboticvehicle 810 rotates about its access in a direction indicated by arrow“R1” in response to a motor that propels the vehicle forward. The axisof rotation of the omni-wheel 818 is nominally oriented perpendicular tothe drive wheel 816 (and the wheels are in orthogonal planes), as shownin FIG. 2. The omni-wheel 818 includes a plurality of rollers 822 thatare located around the periphery of the omni-wheel 818. The rollers 822are mounted on the omni-wheel 818 (via pins or axles, for example) forrotation in the same direction as the drive wheel 816, as indicated byarrow “R2” (i.e., R1 is the same direction as R2). Accordingly, when thedrive wheel 816 is driven, the omni-wheel 818 can serve as a followerwheel that is not driven. The rollers 822 passively rotate as the drivewheel 816 is driven, thereby allowing the vehicle to travel in thedriven direction as indicated by arrow “D” with the rollers serving thepurpose of reducing the friction of the passive omni-wheel 818, at leastthat is the result when the vehicle 810 is moving along a level surface.

The drive wheel 816 can have a single hub or yoke or can have two hubsor yokes (“drive hubs”). The two drive hubs can be arranged to rotatetogether or they can be arranged so that they can rotate with respect toeach other. Allowing one of the drive hubs of the driving wheel torotate freely is useful when pivoting in place. Such an arrangementallows rotation about truly a single point rather than the center of thedriving wheel. This arrangement can also preventing the driving wheelfrom damaging the surface as it slides through the rotation. The drivingwheel can also have curved (and/or textured or coated) points of contact(rim of each hub) such that each side of the driving wheel contacts thesurface in just one point regardless of the curvature. As one example,the rim can be knurled to provide texture. As another example, the rimcan be coated with rubber or polyurethane. Such an arrangement canimprove the consistency of pull force and friction and can also improvethe performance of the chassis and reduce the power consumption on thesteering wheel when pivoting. The drive wheel can include magnets whenadhesion to a ferromagnetic surface is required.

The omni-wheel can include two sets of rollers 822 provided around theperiphery of the wheel and located on each side of the omni-wheel asshown in FIG. 2. The omni-wheel 818 can have two hubs or yokes in whicha set of rollers 822 is provided on each hub. The two hubs can rotatetogether or the two hubs can rotate with respect to each other. Anomni-wheel that includes two sets of rollers permits the omni-wheel toremain normal to the surface as the vehicle maneuvers. This structuralarrangement allows the vehicle to be a fully defined structure withincreased stability, and it increases pull force and traction as thewheel steers. The use of two sets of rollers results in the omni-wheelhaving at least two points of contact with the surface. Since theomni-wheel is mounted orthogonal to the driving wheel, the distancebetween each point of contact and the driving wheel is different. Thesteering wheel could also include a ball caster to maintain the steeringnormal to the surface. The omni-wheel can include magnets when adhesionto a ferromagnetic surface is required.

The omni-wheel 818 provides steering, or rotation, to control therobotic vehicle 810. The vehicle 810 can be steered by driving theomni-wheel 818 using the motor mentioned above, or a second motor(neither separately shown) by using conventional linkages between theomni-wheel and the motor. The omni-wheel rotates in a directionindicated by arrow “R3”. Rotation of the omni-wheel causes the vehicleto turn or steer in a direction indicated by arrows “S”. Controlling therotation of the omni-wheel 818 allows for steering of the vehicle 810.The hinge 820 is constructed to have minimal to no yield as theomni-wheel is driven in the “S” directions so that the vehicle can berotated in the direction “S” without the vehicle folding upon itself andso that movement in the “S” direction of the omni-wheel 818 can becorrelated with a re-orientation of the drive wheel 816 as a result ofthe movement transferred to the drive wheel through the hinge 820.

Accordingly, the drive wheel 816 can be controlled to provide forwardand rearward movement of the vehicle while the omni-wheel 818 is eithera passive, low resistance follower wheel or serving as an active,steering mechanism for the vehicle. The wheels 816, 818 can be activatedand driven separately or at the same time to effect different types ofsteering of the vehicle 810.

The configuration of the wheels of the vehicle provide for excellentmobility and stability while maintaining a relatively small foot print.This permits the robot to fit into small areas and have maneuverabilitythat would be difficult, if not impossible, to achieve with traditionalarrangements such as four wheeled vehicles. For example, a vehiclehaving the described arrangement can be constructed so that it can beeffective on surfaces ranging from 8 inches in diameter to completelyflat surfaces. The drive wheel 816 provides stability to the vehicle. Inparticular, the drive wheel can include a strong magnet which creates apull force between the wheel and a ferromagnetic surface on which thevehicle 810 can be moved, and this structural arrangement assists inresisting tipping of the vehicle. In addition, the drive wheel can havea relatively wide and flat configuration, which further providesstability to the vehicle.

Referring to FIG. 3, the vehicle 810 is shown traversing a curvedferromagnetic surface 1, which, by way of example only, can be a steelpipe. The drive wheel 816 and the omni-wheel 818 can each include amagnet. For example, a magnet can be included in the hub of each ofthese wheels, or in the case of a double omni-wheel, (as shown, in FIG.3) between the two hubs. By connecting the drive wheel and theomni-wheel to respective chassis sections, each chassis section isattracted (via the magnets in the wheels) to theferromagnetic/magnetically inducible material surface (e.g., a materialthat generates an attractive force in the presence of a magnetic field,such as a steel pipe). Alternatively, or in addition, the chassissections themselves could include magnets that provided attractive forcebetween each chassis section and the ferromagnetic surface. As such,when the vehicle traverses a curved or uneven surface, each of thechassis sections can be magnetically attracted to the surface.Meanwhile, the hinge 820 enables the chassis sections to rotate relativeto one another. By this arrangement, the drive wheel 816 and theomni-wheel 18 maintain contact with and normal to the surface alongwhich the vehicle 810 is traveling. A spring 824 can also extend betweenthe two chassis sections 812, 814 and be connected so as to provide anurging force to assist the sections back to the a position in which thetwo wheels are located on the same planar surface with approximatelyzero degrees of rotation between the two chassis sections.

Referring now to FIGS. 4A and 4B, a schematic of the robotic vehicle ona curved surface and on a flat, planar surface are shown, respectively.As shown in FIG. 4A, the chassis sections rotate about the hinge 820 sothat the wheels maintain contact with the curved surface 2 on which thevehicle is traveling. Accordingly, the hinge is positioned such that itallows the steering wheel to adjust to the curvature while preventingthe rest of the chassis from touching. Without the hinge 820, thechassis would remain in a straight line configuration and one of thewheels could fail to maintain contact the curved surface, or may only bein partial contact with the curved surface (e.g., only an edge of awheel may maintain contact). Failure of one or two of the wheels tomaintain contact with the traveling surface can have significantconsequences. First, parts of the wheel such as the perimeter edges cancome into contact with the surface which can introduce drag and wear onthe parts as the vehicle continues along the surface. Second, thatfailure can result in a significant drop in the attractive force betweenthe magnets of the chassis and surface. This could have a catastrophicconsequence, such as when the vehicle is traversing a vertical orinverted surface, in which the vehicle fails to maintain magneticpurchase with the surface and actually decouples from the surface.Decoupling of the vehicle can result in damage to the vehicle sufferedas a result of the fall, present a danger to workers in the area, and/orcould result in the vehicle becoming stuck, which could present furtherproblems. In addition, the hinge and chassis can be arranged to maintaina low center of mass of the vehicle.

As shown in FIG. 4B, the vehicle 810 is disposed on a flat surface 3.The hinge 820 can include rotation stops 826 and 828. These can bemating surfaces on each of the first and second chassis sections forexample. The rotations stops can be positioned to prevent undesiredrotation about the hinge 820, or to limit rotation to a set range ofdegrees, such as when the vehicle is on a flat surface. For example, thehinges can prevent the vehicle from folding upon itself when on a flatsurface such that the hinge joint is dragged on the surface. The stopscan also be spaced to allow a limited amount of rotation in both up anddown directions. Accordingly, the vehicle can rotate about the hinge toadapt to both concave and convex surfaces. As such, the vehicle can beused on the outside of a pipe (convex surface) as well as in the insideof a tank (concave surface) without structural changes to the vehicle.The degree of freedom can permit movement in both the up and downdirections, which can increase the vehicle's ability to traverse bothconvex surfaces (e.g., outside of a pipe) and concave surfaces (such asa tank surface). The width of the omni-wheel and the magnets thatprovide attractive force between the wheel and the surface help resistunwanted movement in the up and down directions. The omni-wheel, by itswidth and its magnets (which can provide two points of contact with thesurface), is biased to be normal to the traveling surface. Accordingly,the omni-wheel itself provides a resistive force to over rotation of thevehicle about the hinge.

In addition, the hinge can have other limited degrees of freedom, whichcan be accomplished by incorporating some play in the hinge design. Thisplay can improve the function of the robot as it moves along particulartrajectories that induce a twisting motion between the two chassissections, such as when the vehicle is traveling in a helical patternaround a pipe.

The robotic vehicle 810, including the orientations of its magneticwheel and the hinged chassis, provides significant advances in mobility.It is possible to accomplish a complete 180° turn while traversing ahalf circle (e.g., steel pipe) that has a diameter only slightly largerthan the diameter of the drive wheel. The vehicle can be used to moveand carry inspection equipment. Other uses for such a vehicle having theabove described chassis design can be used to move and transportgoods/personnel on magnetically inducible materials, such as the steelframework of a skyscraper that is being constructed (or forinspection/maintenance after construction by providing magnetic purchaseto the steel structure) or the side of a large vessel.

A vehicle as described above can transverse steel surfaces withdiameters of as little as 6″ and potentially even smaller, with theability to move in any direction and to any orientation. The movement ofthe vehicle can include longitudinal movement, circumferential movement,helical movement, 360 degree pivoting around a fixed point. The vehiclecan overcome obstacles such as welds or patches of up to at least onehalf inch. The vehicle is cable of performing these maneuvers on theunderside of steel surfaces, including both internally within a pipe andexternally on multiple structures. The vehicle can also negotiate elbowsor other turns in pipes on both the convex and concave surfaces.Additionally, the vehicle, as a result of its pivoting motion, canovercome certain types of obstacles which would not be easy for a normalwheel to drive over. Accordingly, the vehicle can temporarily use theomni-wheel as the primary locomotive accessory (while the ‘drivingwheel’ remains primarily in place). The design of the vehicle alsoallows the vehicle to transverse very narrow surfaces (such as the sideof a beam, very small pipe, etc.) due to its in-line configuration. Theminimum width of such a surface is limited only by the inner distancedbetween the two yokes of the magnetic driving wheel.

It should be understood that various combination, alternatives andmodifications of the present invention could be devised by those skilledin the art. The present invention is intended to embrace all suchalternatives, modifications and variances that fall within the scope ofthe appended claims.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

The invention claimed is:
 1. A robotic vehicle chassis, comprising: afirst chassis section, the first chassis section including at least onemotor; a second chassis section; a hinge joint connecting the first andsecond chassis sections such that the first and second chassis sectionsare capable of rotation with respect to each other in at least a firstdirection; a drive wheel mounted to the first chassis section, whereinthe drive wheel includes a first hub and a second hub, the first andsecond drive hubs being configured to be actuated to rotateindependently by the at least one motor; an omni-wheel mounted to thesecond chassis section, the omni-wheel being mounted at an angleorthogonal with respect to the drive wheel and configured to bepassively driven by the drive wheel; at least a first magnet connectedto at least the drive wheel or the first chassis section; and at least asecond magnet connected to at least the omni-wheel or the second chassissection, wherein the at least first and second magnets maintain anattractive force between the first chassis section and the surface andthe second chassis section and the surface, respectively, wherein thesurface is ferromagnetic, wherein the hinge joint rotates in response tothe curvature of a surface the vehicle is traversing.
 2. The roboticvehicle chassis of claim 1, further comprising: a spring elementextending between the first and second chassis section, the springelement providing a force that urges the first and second chassissections into a normal position in which there is a zero degree ofrotation between the first and second chassis sections.
 3. The roboticvehicle chassis of claim 1, wherein the omni-wheel includes a first andsecond set of rollers located on each side of the omni-wheel such thatthe first and second set of rollers are located to maintain at least twopoints of contact with the surface.
 4. The robotic vehicle chassis ofclaim 3, wherein the first and second set of rollers are supported by afirst and second hub, respectively, where the first and second hubs areconfigured to rotate freely with respect to each other.
 5. The roboticvehicle chassis of claim 1, wherein the drive wheel includes a first andsecond drive hub, wherein the first and second drive hubs are configuredto selectively rotate freely with respect to each other.
 6. The roboticvehicle chassis of claim 5, wherein the contact surfaces of the drivehubs are curved such that each side of the driving wheel contacts thesurface at a single point.
 7. The robotic vehicle chassis of claim 6,wherein points of contact of the drive hubs are textured.
 8. The roboticvehicle chassis of claim 7, wherein points of contact of the drive hubsare knurled.
 9. The robotic vehicle chassis of claim 6, wherein pointsof contact of the drive hubs are coated.
 10. The robotic vehicle chassisof claim 9, wherein points of contact of the drive hubs have a rubbercoating.
 11. The robotic vehicle chassis of claim 9, wherein points ofcontact of the drive hubs have a polyurethane coating.
 12. The roboticvehicle chassis of claim 1, wherein a single power source provides powerto the first and second chassis sections and the at least one motor fordriving the drive wheel.
 13. The robotic vehicle chassis of claim 1,wherein a first motor actuates the first hub and a second motor actuatesthe second hub.
 14. A robotic vehicle chassis, comprising: a firstchassis section; a second chassis section; a hinge joint connecting thefirst and second chassis sections such that the first and second chassissections are capable of rotation with respect to each other in at leasta first direction; a drive wheel mounted to one of the first and secondchassis sections, wherein the drive wheel includes a single hub, andwherein the drive wheel has a curvature such that the single hubcontacts the surface at a single point; an omni-wheel mounted to theother of the first and second chassis sections; the omni-wheel beingmounted at an angle orthogonal with respect to the drive wheel; at leasta first magnet connected to at least the drive wheel or the chassissection to which the drive wheel is mounted; and at least a secondmagnet connected to at least the omni-wheel or the chassis section towhich the omni-wheel is mounted, wherein the at least first and secondmagnets maintain an attractive force between the first chassis sectionand the surface and the second chassis section and the surface,respectively, wherein the surface is ferromagnetic, wherein the hingejoint rotates in response to the curvature of a surface the vehicle istraversing.
 15. A robotic vehicle chassis, comprising: a first chassissection; a second chassis section; a hinge joint connecting the firstand second chassis sections such that the first and second chassissections are capable of rotation with respect to each other in at leasta first direction; at least one rotation stop positioned to preventundesired rotation about the hinge joint; a drive wheel mounted to thefirst chassis section; an omni-wheel mounted to the second chassissection, the omni-wheel being mounted at an angle orthogonal withrespect to the drive wheel; at least a first magnet connected to atleast the drive wheel or the first chassis section; and at least asecond magnet connected to at least the omni-wheel or the second chassissection, wherein the at least first and second magnets maintain anattractive force between the first chassis section and the surface andthe second chassis section and the surface, respectively, wherein thesurface is ferromagnetic, wherein the hinge joint rotates in response tothe curvature of a surface the vehicle is traversing.
 16. The roboticvehicle chassis of claim 15, wherein the at least one rotation stop isincluded in the hinge joint.
 17. The robotic vehicle chassis of claim15, wherein the at least one rotation stop includes mating surfaces oneach of the first chassis section and the second chassis section. 18.The robotic vehicle chassis of claim 15, wherein the at least onerotation stop includes mating surfaces on the first chassis section andon the omni-wheel.
 19. The robotic vehicle chassis of claim 15, whereinthe at least one rotation stop limits rotation of the hinge joint to aset range of degrees.
 20. The robotic vehicle chassis of claim 19,wherein the set range of degrees limits rotation of the hinge joint tobe in only one direction from a linearly aligned position of the firstand second chassis sections.
 21. The robotic vehicle chassis of claim15, wherein the at least one rotation stop is adjustable to allow thehinge to rotate to adapt to both concave and convex surfaces.
 22. Therobotic vehicle chassis of claim 15, wherein the at least one rotationstop provides resistance to rotation in a direction other than the firstdirection.